The food service industry serves food from a box-like refrigeration unit having one or more openings to receive pans of food. There can be work surfaces that are approximately waist high that house the pans, and often times, there can be a storage area below for refrigerated or frozen food. There are many factors that give manufacturers trouble in properly maintaining the food temperature not only in the storage area, but also the pans of food ready for service on the work surface. Changing ambient temperatures can also make these units susceptible to improperly maintained temperatures.